Zero is one of the
higher-ranked agents of "NESTS". The designer, C.A.C Yamasaki, admits
basing Zero off a certain character from the manga Fist of the North Star.
He begins to secretly build his own weapon from NESTS' technology called the
"Zero Cannon", setting it to operate. He sets his plans into motion in
The King of Fighters 2000. There, he impersonates a military commander named
Ling and uses his persona as a decoy to stop the military resistance against
him. Depending on the actions of the player, his plans are foiled by either Heidern
or Kula, who is sent to execute him for his treacherous
acts.

The Zero
in The King of Fighters 2000 is revealed to be a clone from the Original
Zero, Zero, who
appears as a sub-boss in The King of Fighters 2001. He was created
because the supervising designer to his character claimed to be dissatisfied
with Zero's design in 2000. Unlike his clone, Zero is extremely loyal to the
NESTS syndicate and was disgusted to learn of his clone's attempted coup d'état.
Willing to clear his reputation of his clone's actions, Zero is commanded to
destroy the winners of The King of Fighters tournament. He traps the winning
team in a space ship that was disguised as a blimp. When he is defeated, he
urges the team to escape the collapsing ship and dies on board the vessel. The
original Zero is voiced by Toshimitsu Arai, while the clone is voiced by Kinta
Futogane.

I thought the
"original"
Zero was pretty cool... as in, the KOF2000 version. ;) I guess SNK thought they could get away with a quick head swap and make a
new character? This white-haired Zero has a cool aura about him, and I guess this
guy's the real deal, according to the storyline. Even though he had a lot of the
"other" Zero's moves, he did have some unique mannerisms & moves
of his own. For some reason I do like the other Zero better, though.